In present mobile communications networks, such as 3rd Generation Partnership Project (3GPP) communications networks including Global System for Mobile communication (GSM), Universal Mobile Telecommunications Service (UMTS) or Long Term Evolution (LTE), each user (i.e. subscribe)r is subject to charging and billing for individual network resource usage.
GSM/UMTS/LTE networks provide functions that implement offline and/or online charging mechanisms for the user's network resource usage in the form of for instance a voice call of certain duration, the transport of a certain volume of data, the submission of a Multimedia Messaging Service (MMS) of a certain size, etc.
In both offline and online charging, charging information for network resource usage is collected concurrently with that resource usage.
However, in offline charging, the resource usage is reported from the network after the resource usage has occurred for the purpose of subscriber billing. Hence, offline charging is a mechanism where charging information does not affect, in real-time, the service rendered.
To the contrary, in online charging, a subscriber account, located in an online charging system, is queried prior to granting permission to use the requested network resource(s). Thus, authorization for the network resource usage must be obtained by the network prior to the actual resource usage to occur. This authorization is granted by a so called Online Charging System (OCS) upon request from the network and may be limited in scope (e.g. volume of data or duration), therefore the authorization may have to be renewed from time to time as long as the user's network resource usage persists.
FIG. 1 illustrates an online charging architecture of a 3GPP network. As is illustrated, offline and online charging mechanisms are implemented on three levels: (1) bearer level in the core network (CN) domain, e.g. in Evolved Packet Core (EPC) in LTE, (2) service level, e.g. as MMS, and (3) subsystem level, e.g. in Internet Protocol Multimedia System (IMS).
A Charging Trigger Function (CTF) 10 generates charging events based on the observation of a user's network resource usage and forwards the charging events to an Online Charging Function (OCF) 11 of an Online Charging System (OCS) 12 in order to obtain authorisation for the chargeable event/network resource usage requested by the user.
The authorisation returned by the OCF 11 to the CTF 10 comprises a so called quota, i.e. an apportionment of the amount of network resources allowed to be consumed by the user. Thus, in practice, the OCF 11 reserves credit from a subscriber account and returns the corresponding quota (e.g. units specifying the number of minutes or bytes allowed for the requested service) to the CTF 10, which in its turn uses the provided quota to supervise the actual network resource consumption.
When the quota is used up, the CTF 10 either issues another charging event, requesting further units to be apportioned, or terminates the session—e.g. a voice call, an IMS session, or an IP connectivity access network (IP CAN) session—associated with the quota (or requests some other network element to terminate the session) if previously instructed to do so by the OCF 11. Once the session is terminated, the consumed units are reported back to the OCF 11 with a final charging event. The credit control session is then terminated, and the OCF 11 returns the value of any unused quota (as reported by the CTF 10) to the subscriber's account.
FIG. 1 further illustrates that the OCS 12 comprises a Rating Function (RF) 13 for determining a value of the network resource usage described in the charging event received by the OCF 11 from the network, on behalf of the OCF 11. The various interfaces, commonly known as reference points, between the illustrated logical charging functions are denoted Ro/CAP, Rc and Re.
The OCS 12 further comprises an Account Balance Management Function (ABMF) 14, which is where the subscriber's account balance is located within the OCS 12.
It is also possible to have a 3rd party pay the bill of the user, for instance a so called over-the-top (OTT) service provider, such as Netflix, Spotify, Facebook, etc. This is commonly referred to as sponsored data connectivity, where the 3rd party (a.k.a. sponsor) has a business relationship with the network operator and reimburses the operator for the user's data connectivity to a service provided by the sponsor (or alternatively that, the user pays for the connectivity with a transaction which is separate from the subscriber's normal charging in the network).
In case of sponsored data connectivity, the CTF 10 reports sponsored use of network resources together with the subscriber's use of offline charging services. The OCS 12 will thus have to aggregate sponsored usage over all subscribers offline charging data for settlement with the sponsor, which is a cumbersome process.
A further problem in the existing solution is that a great amount of requests for use of sponsored services may be received at the CTF 10 from individual users and that the OCS 12 will receive a corresponding number of requests for authorisation from the CTF 10 to access the sponsored services, thereby generating a great amount of traffic in the network.